JP2013532212A - Improvement of composite materials - Google Patents

Abstract

  Blending a liquid curable resin and a curing agent having a melting point greater than 100 ° C. to form a liquid blend of the curable resin and the curing agent, configured for the blended curable resin and the curing agent Curing, comprising impregnating at least a portion of the fiber array to form a curable composite material, and then subjecting the composite material to an elevated temperature at a pressure of 3 absolute bar or less to form a cured composite material; A method for producing a composite material.

Description

  The present invention is particularly concerned with improving the manufacture of composite materials, but is not dedicated to application in aerospace structures.

  Composite materials have well-proven advantages over conventional building materials, especially in achieving excellent mechanical properties at very low material densities. As a result, the use of such materials has become increasingly widespread, and their fields of application range from “industrial” and “sports and leisure” to high performance aerospace components.

  The prepreg includes a fiber array impregnated in a resin such as an epoxy resin, and is widely used in the production of the composite material described above. Typically, several such prepregs are “laid up” as desired, and the resulting laminate is typically cured by exposure to elevated temperatures to produce a cured composite laminate. To do.

  Such cured composites necessarily have some degree of encapsulated gas, or porosity, which can reduce the mechanical strength of the material. For example, air bubbles can occur in the resin manufacturing process, fiber impregnation can be incomplete, and both lead to the presence of porosity.

  In order to allow curing to occur, a curing agent that imparts a curing function by reacting with a functional group on the resin to form a crosslink is incorporated into the resin. Such curing agents are typically blended with curable resins at low temperatures to prevent thermal hazards and thereby prevent premature reaction between the resin and the curing agent. . The selection of the curing agent strongly affects the mechanical properties of the cured resin.

  For aerospace applications, composite materials must meet very strict requirements regarding porosity and mechanical strength. For this reason, aerospace composites are mostly cured only by autoclave curing. Such curing is carried out at high pressures and temperatures, and the porosity is very low and therefore tends to produce good mechanical properties. It is believed that due to the high pressure, any encapsulated gas must be in solution, with the result that the composite material being cured remains essentially void-free.

  However, autoclave curing is expensive and time consuming to operate. Therefore, methods have been sought for curing aerospace quality composites by deautoclaving.

  The present invention aims to reduce or at least avoid the problems defined above and / or provide improvements in general.

  According to the present invention there is provided a method, material and use as defined in any one of the appended claims.

  The present invention relates to a method for producing a curable composite material, which blends a liquid curable resin and a curing agent having a melting point greater than 100 ° C. to form a liquid blend of the curable resin and the curing agent. Step, impregnating at least a portion of the constituent fiber array to the blended curable resin and curing agent to form a curable composite material, after which the composite material is at a pressure of 3.0 absolute bar or less And curing at high temperature to form a cured composite material.

  It has been found that when a curing agent known to impart good mechanical properties to the cured material is employed, unacceptable porosity occurs. However, the inventors have found that composite materials having aerospace quality mechanical properties and porosity can be prepared without the use of autoclave curing. This selects a curing agent with a high melting point known to confer good mechanical performance, where the curable resin is liquid and the curing agent dissolves in the liquid resin, This is accomplished by blending with the resin at a temperature that forms a uniform liquid blend.

  In one preferred embodiment, the curing agent is in the range of 70 to 220 ° C, preferably in the range of 70 to 220 ° C, more preferably in the range of 90 to 200 ° C, and even more preferably in the range of 100 to 180 ° C. Most preferably has a melting point in the range from 120 to 180 ° C., or a combination of the foregoing ranges. The melting point is measured by DSC (Differential Scanning Calorimetry) according to ASTM D3418.

  In a preferred embodiment, the solid curing agent has a small particle size, typically in the range of 0.01 microns to 5 mm, more preferably in the range of 0.1 microns to 1 mm, more preferably 0.5. The range from micron to 0.5 mm, even more preferably from 1 micron to 0.1 mm, most preferably from 10 micron to 0.1 mm and / or combinations of the foregoing ranges. The particle size is derived from the particle size distribution measured by ASTM D1921-06el standard test method (Method A) for the particle size (sieving analysis) of plastic materials. Smaller particles have the advantage that they dissolve faster and thereby reduce the residence time in the blender and increase the flow of resin through the blender. This in turn reduces the risk of uncontrolled release of the exothermic energy of the blend and reduced resin activity after blending. If the blender is an extruder, this results in a shorter extruder, which reduces the cost of the processing equipment.

  After high temperature blending causes dissolution of the curing agent in the resin, and subsequently cooling the blend, the blend forms a reinforced resin that, in combination with the fiber array, provides a molding material. Suitable for

  As long as the curing agent has a melting point higher than 100 ° C., it can be selected from a wide variety of suitable materials known in the art. Better mechanical performance can be achieved if a higher melting point curing agent is selected, and therefore a melting point higher than 120 ° C. is preferred, more preferably the melting point is higher than 140 ° C.

  Suitable curing agents include, by way of example, diaminodiphenyl sulfones such as 3,3 ′ DDS and 4,4 ′ DDS, bis-aminophenyl fluorene such as 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (3 -Chloro-4-aminophenyl) fluorene, 3,4'-oxydianiline, 4,4'-diaminobenzoylanilide, 1,3'-bis (4-aminophenoxyl) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 4-aminophenyl 4-aminobenzoate, bis (4-aminophenyl) terephthalate, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (-Aminophenoxy) phenyl] hexafluoropropane, 2,5-bis (4-aminophenoxy) biphenyl, 4-4 -Bis (4-aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) benzophenone, bis (3-amino-4-hydroxyphenyl) sulfone, 4,4'diaminodiphenyl ether, bis (4- (4 -Aminophenoxy) phenylsulfone.

  The most preferred curing agents are diaminodiphenyl sulfones, such as 3-3'DDS (melting point 172 ° C) and 4-4'DDS (melting point 176 ° C).

  The curable resin may be selected from, for example, epoxy or isocyanate, and preferably the curable resin is an epoxy resin.

  Suitable epoxy resins may include monofunctional, difunctional, trifunctional and / or tetrafunctional epoxy resins.

  Suitable bifunctional epoxy resins include, by way of example, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A (optionally brominated), phenolic and cresolic epoxy novolacs, glycidyl of phenol-aldehyde adducts. Ether, glycidyl ether of aliphatic diol, diethylene glycol diglycidyl ether, aromatic epoxy resin, aliphatic polyglycidyl ether, epoxidized olefin, brominated resin, aromatic glycidyl amine, heterocyclic glycidyl imidine, heterocyclic glycidyl amide, fluorine And epoxy resin, glycidyl ester, or any combination thereof.

  The bifunctional epoxy resin may preferably be selected from diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol A, diglycidyl dihydroxynaphthalene, or any combination thereof.

  Suitable trifunctional epoxy resins include, for example, phenolic and cresolic epoxy novolaks, glycidyl ethers of phenol-aldehyde adducts, aromatic epoxy resins, aliphatic triglycidyl ethers, dialiphatic triglycidyl ethers, aliphatic poly Mainly composed of glycidyl ether, epoxidized olefin, brominated resin, triglycidyl aminophenyl, aromatic glycidyl amine, heterocyclic glycidyl imidine, heterocyclic glycidyl amide, glycidyl ether, fluorinated epoxy resin, or any combination thereof Things can be mentioned.

  Suitable tetrafunctional epoxy resins include N, N, N ′, N′-tetraglycidyl-m-xylenediamine (named Tetrad-X from Mitsubishi Gas Chemical Company and Erisys GA-240 from CVC Chemicals). And N, N, Ν ′, Ν′-tetraglycidylmethylenedianiline (for example, MY721 manufactured by Huntsman Advanced Materials).

  In order for the curing agent and curable resin to be blended to form a uniform liquid, the blending temperature must be high enough to allow the curing agent to dissolve in the liquid resin, which is It may be lower than the melting point of the agent. However, if the blending temperature is too high, a premature reaction is initiated between the curing agent and the curable resin.

  The blending temperature can range from the temperature at which the curing agent dissolves in the curable resin to a temperature below the melting point of the curing agent. Thus, typically the blending temperature is from 60 to 180 ° C, preferably from 80 to 160 ° C, more preferably from 90 to 150 ° C. Most preferably, the curing agent is blended with the resin to dissolve the curing agent at a temperature in the range of 70 to 150 ° C, in the range of 90 to 140 ° C, preferably in the range of 100 to 130 ° C.

  When curable resins and curing agents are blended at high temperatures, they tend to react more prematurely, which can lead to thermal safety hazards or runaway exothermic reactions. In addition, high blending temperatures increase the level of resin activation, which allows the resin to cure as the interpolymer network is formed, so blending effectively reduces resin activity. To do. Therefore, in the case of a blending operation at a high temperature, it is preferable to carry out in as short a time as possible to ensure good blending.

  In a preferred embodiment, the blending is performed during an in-line or continuous process. Preferably, only a portion of the liquid resin is blended with the curing agent at any point in time to control the temperature of the blend and prevent the blend from prematurely curing. The residence time in the blend is selected so that the solid curing agent dissolves in the curable resin. The residence time in the blender can range from 1 second to 10 minutes, preferably from 30 seconds to 5 minutes, more preferably from 30 seconds to 2 minutes. Residence time is defined by the flow of liquid resin through the blender and the dimensions of the blender, ie residence time = blender volume / flow velocity through the blender.

  The blend may be cooled after blending. Cooling may be performed by increasing the surface area of the reinforced resin to allow rapid heat transfer. The resin may be exposed to a refrigerant such as air or a cooler or chiller. The blend may be cooled by casting the blend or impregnating the constituent fiber array.

  In a further embodiment, the liquid curable resin comprises a toughening material or toughening agent. Preferably, the toughening material or toughening agent is a thermoplastic material. Thermoplastic toughening can be any of the common thermoplastic materials used to toughen thermoset aerospace resins. The toughening agent may be a polymer, which may be in the form of a homopolymer, copolymer, block copolymer, graft copolymer, or terpolymer. The thermoplastic toughening agent may be a thermoplastic resin having single or multiple bonds selected from carbon-carbon bonds, carbon-oxygen bonds, carbon-nitrogen bonds, silicon-oxygen bonds, and carbon-sulfur bonds. One or more repeating units may be a residue, an amide residue, an imide residue, an ester residue as follows for either the main polymer backbone or the side chain suspended on the main polymer backbone: It may be present in polymers in which groups, ether residues, carbonate residues, urethane residues, thioether residues, sulfone residues and carbonyl residues are incorporated. The polymer may have a linear or branched structure. The thermoplastic polymer particles may be either crystalline or amorphous or partially crystalline.

  Suitable examples of thermoplastic materials used as toughening agents include polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyether, polyester, polyimide, polyamideimide, polyetherimide, polysulfone, polyurethane , Polyethersulfone, polyetherethersulfone and polyetherketone. Polyether sulfones and polyether ether sulfones are a preferred type of thermoplastic material. The amount of toughener present in the uncured resin composition usually ranges from 5 to 30 wt%, preferably the amount of toughener ranges from 10 wt% to 20 wt%.

  Examples of commercially available thermoplastic toughening agents include Sumitomo Chemicals Co. Sumikaexcel 5003P PES available from (Osaka, Japan), Ultrason E2020P SR available from BASF (Ludwigshafen, Germany), and available from Solvay Engineered Polymers ether unit, AuburnUl ether ethers, AuburnAll ether ethers Solvay Radel A which is a copolymer of Optionally, these PES or PES-PEES copolymers may be used in a densified form. The densification process is described in US Pat. No. 4,945,154.

  Therefore, preferably, prior to fiber impregnation, the blended curing agent and curable resin is greater than 100 ° C, preferably less than 10 minutes, preferably less than 2 minutes, more preferably less than 1 minute, preferably 120 Higher than 140C, more preferably higher than 140 ° C.

  Preferably, prior to fiber impregnation, the temperature of the blended hardener and curable resin is greater than 100 ° C, preferably 120 ° C for less than 10 minutes, preferably less than 2 minutes, more preferably less than 1 minute. Higher, more preferably higher than 140 ° C.

  It has also been found that the final porosity can be further reduced by applying a vacuum during the resin blend.

  The inventors have found that the inherent difficulty appears when the temperature of a large amount of resin rises in a short time. Heat is usually transferred by heating the container, and the container contains a curable resin, thereby creating a temperature gradient inside the container.

  It has been found that a convenient heating process involves the passage of heat through the curable resin and hardener through the narrow diameter conduit, resulting in a shorter distance for heat to conduct before reaching the blend temperature. This means that when the central material begins to heat, the material near the wall that was initially heated has not been at the blending temperature for too long.

  Thus, preferably, the above process involves liquid curing agent and liquid curable resin in a conduit having a characteristic diameter of less than 20.0 cm, preferably less than 10.0 cm, more preferably less than 5.0 cm. Including passing. This characteristic diameter is considered the inner diameter of a conceptual conduit having a circular cross section with the same surface area as that of the cross section of the conduit.

  Thus, good results are obtained by heating the wall of the conduit to a temperature of 100 to 300 ° C.

  In a preferred embodiment, the conduit includes a mixing element. The mixing element may be stationary or dynamically movable. One particularly preferred process uses a screw extruder to provide conduits and mixing elements.

  Once the blending operation is performed, it is important to cool the blended curable resin to minimize any undesirable premature reaction and thermal hazard.

  Once prepared, the blended curable resin is then impregnated into the constituent fibers in a manner known in the art. Although the degree of impregnation can vary, in aerospace applications it is usually intended to impregnate the fibers almost completely, and in this embodiment almost all the fibers are in contact with the curable resin. Yes.

  Typically, the constituent fibers are tabular, so that they form a once impregnated prepreg. The constituent fibers can be in the form of irregular, knitted, non-woven, multiaxial, or any other suitable pattern. However, preferably they are substantially unidirectional.

  The constituent fibers may include chopped (ie, broken by stretching), selectively discontinuous or continuous fibers.

  The constituent fibers can be made from a wide variety of materials such as carbon, graphite, glass, aramids of metallized polymers, and mixtures thereof. Carbon fiber is preferred.

  Although the curable composite material can be formed into a wide variety of structural shapes, it is preferably formed into an aerospace structural member.

  Once formed, the curable composite material is cured by exposure to high temperatures. However, the pressure during curing does not exceed 3.0 absolute bar.

  The curing process may be carried out at a pressure below 2.0 bar absolute. In particularly preferred embodiments, the pressure is below atmospheric pressure. This curing process can be performed at one or more temperatures ranging from 80 to 200 ° C. and for a time sufficient to produce the desired degree of curing.

  Curing at a pressure close to atmospheric pressure can be realized by a so-called vacuum bag method. This involves placing the composite material in an airtight bag and evacuating the inside of the bag. This has the effect of bringing the compaction pressure received by the composite material to atmospheric pressure, depending on the degree of vacuum applied.

  Once cured, the composite material can be suitable for use in structural applications, such as aerospace structures.

  Such cured composite materials have a low porosity in volume porosity of less than 3.0%, preferably less than 2.0%, more preferably less than 1.0%, or even less than 0.5%.

  In a further embodiment, a temperature from 70 ° C. to 150 ° C., preferably from 90 ° C. to 140 ° C., or from 90 ° C. to 150 ° C., most preferably from 100 ° C. to 140 ° C. In the combination of the above ranges, the liquid curable resin and the curing agent are blended in-line or continuously, and the volume porosity is less than 4.0%, preferably less than 3.0%, more preferably 2. There is provided the use of a reinforced resin, prepared by forming a curable composite material having a porosity of less than 0%, followed by curing in a deautoclave, into a fiber array. The porosity ranges from 0% to 5.0%, from 0% to 4%, 3%, 2%, or 1%, or from 0.5% to 4%, 3%, 2% or 1 % And / or any combination of the aforementioned porosity.

  De-autoclave curing is performed at temperatures ranging from 60 ° C to 200 ° C, temperatures ranging from 80 ° C to 180 ° C, preferably temperatures ranging from 80 ° C to 160 ° C, most preferably from 80 ° C to 140 ° C. It may be carried out at a range of temperatures and / or combinations of the aforementioned temperatures and / or at pressures below atmospheric pressure.

  “De-autoclaving” curing herein refers to any technique that allows a composite material to cure at elevated pressure without the use of an autoclave. Autoclaves typically include an exhaust chamber formed by a metal sealable housing in which a composite material or molding is placed. The chamber is evacuated while the molding is cured to a very low vacuum pressure. As discussed, autoclaves are very expensive and the dimensions of the exhaust chamber limit the size of the moldings that can be processed. The material according to the invention is particularly suitable for vacuum bag processing which does not have the aforementioned disadvantages of autoclaves.

  Next, in the following examples, the present invention will be described with reference to the following drawings.

In FIG. 1, a cross-sectional image of a cured laminate according to Comparative Example 1 is shown along with its C-scan. In FIG. 2, a cross-sectional image of the cured laminate according to Example 1 is shown along with its C-scan. 1 is a schematic depiction of a vacuum bag curing processing apparatus used in an example. It is a figure which shows the hardening cycle used in the Example.

(Comparative Example 1-Preparation of resin by conventional mixing)
To the Winkworth Z-blade mixer, 1405 g MY721 (Huntsman), 1405 g MY0510 (Huntsman), and 845 g 5003P polyethersulfone powder (manufactured by Sumitomo) were added. The temperature was raised to 130 ° C. and mixed for 2 hours until the polyethersulfone was dissolved in the resin. The resin mixture was then cooled to 80 ° C., after which 1210 g of 3,3 ′ DDS and 135 g of 4,4 ′ DDS were added and mixed for 20 minutes to disperse the DDS powder. The finished resin was then used to make a fully impregnated unidirectional prepreg tape with an area weight of 145 g according to standard film transfer methods. The fiber used was Hextow IM7-12K and the resin content was 35%.

(Example 1-Preparation of resin by mixing in an extruder)
A resin identical to the above was produced by applying a vacuum of −0.8 bar gauge at a barrel temperature of 110 ° C. and introducing the DDS powder into the resin in a twin screw extruder with an inner diameter of 25 mm. In this case, the DDS powder is dissolved in the resin.

(Example 2-Preparation of laminate)
A unidirectional laminate according to Example 1 having dimensions of 400 × 400 × 5 mm was prepared using 32 prepregs in a pseudo isotropic layup form. The prepreg laminate was disassembled every four sheets under vacuum. The laminate was then cured in an oven according to a conventional curing cycle (illustrated in FIG. 4) and a vacuum bag processing configuration (illustrated in FIG. 3).

  The fiber laminate is made in the same way, except that 12 sheets are used to a thickness of about 4.3 mm.

(Example 3-C-scan and measurement of porosity)
The cured laminate was C-scanned with an Olympus Omniscan apparatus to evaluate the quality of the laminate. In this test, an ultrasonic probe is used to measure the presence of voids, shown as white dots on the two-dimensional image of the laminate. From these C-scan data, a representative sample of the laminate was cut out and polished, and observed under a microscope. The percentage of void area was calculated using image analysis of micrographs.

  In FIG. 1, an image obtained for Comparative Example 1 is shown, indicating a porosity of 3.24 vol%.

  FIG. 2 shows the image obtained for Example 1 according to the invention, showing a porosity of 0.17 vol%.

  The following briefly introduces alternative embodiments of the present invention.

In one embodiment, a method of making a curable composite material is provided, the method blending a liquid curable resin and a curing agent having a melting point greater than 100 ° C. to form a liquid form of the curable resin and the curing agent. Forming a blend, impregnating at least a portion of the constituent fiber array to the blended curable resin and curing agent to form a curable composite material, after which the composite material is 3 absolute bar Curing to an elevated temperature at the following pressure to form a cured composite.
In another embodiment, the curing agent has a melting point greater than 120 ° C, preferably the melting point is greater than 140 ° C.
In a further embodiment, the curing agent comprises diaminodiphenyl sulfone.
In one embodiment, the blending is carried out at a temperature from 60 to 180 ° C, preferably from 80 to 160, more preferably from 90 to 150 ° C.
In a further embodiment, prior to fiber impregnation, the blended curing agent and curable resin is greater than 100 ° C, preferably 120 ° C for less than 10 minutes, preferably less than 2 minutes, more preferably less than 1 minute. Higher, more preferably higher than 140 ° C.
In one embodiment, a vacuum is applied during resin blending.
In a further embodiment, the method comprises passing the liquid curing agent and curable resin blend through a conduit having a characteristic diameter of less than 20 cm, preferably less than 10 cm. The wall of the conduit can be heated to a temperature of 100 to 300 ° C. The conduit may include a mixing device.
In another embodiment, a screw extruder is used to provide the conduit and mixing equipment.
In a further embodiment, the constituent fibers are tabular, so that they form a once-impregnated prepreg.
In another embodiment, the curable composite material is molded into an aerospace structural member.
In another embodiment, the curing process is performed at a pressure less than 2.0 absolute bar, preferably less than atmospheric pressure. Curing may be performed by a so-called vacuum bag method.
In one last embodiment, the cured composite material has a porosity of less than 3.0%, preferably less than 2.0%, more preferably less than 1.0%, most preferably less than 0.5% in volume porosity. Have

  Accordingly, a method for preparing a resin and a curable composite, wherein the composite can be cured using conventional equipment that does not have an autoclave when the composite is laid up to form a molded product. The porosity in the object is also reduced, which provides a method of preparation that often involves a curing treatment of the curable composite in an autoclave.

Claims (17)

a. Preparing a liquid curable resin;
b. Providing the curing agent as a solid;
c. In at least a portion of the liquid curable resin, the curing agent is blended in-line or continuously, and the curing agent is dissolved at a temperature of 70 ° C. to 150 ° C., preferably 90 ° C. to 140 ° C. And d. A method of preparing a reinforced resin comprising the step of cooling the blend after dissolution to form a reinforced resin.   In-line blending is performed in the blender during the residence time from addition of the curing agent to dissolution of the curing agent, preferably the residence time in the blender ranges from 1 second to 10 minutes, most The method of claim 1, preferably in the range of 30 seconds to 5 minutes.   The method according to claim 1 or 2, wherein the cooling is carried out by increasing the surface area of the reinforced resin exposed to the refrigerant.   4. A method according to any one of claims 1 to 3, wherein the blend is cooled by casting the blend or by impregnation of the constituent fiber array.   The method according to claim 1, wherein in step a) the liquid curable resin comprises a toughening material.   A method for producing a curable composite material comprising preparing a reinforced resin as defined in any one of claims 1 to 5, wherein at least a part of the constituent fiber array is impregnated.   7. The method according to any one of claims 1 to 6, wherein the curing agent has a melting point above 100 ° C.   A cured composite material comprising the step of forming the cured composite material after the process according to claim 6 or 7 by subjecting the composite material to a temperature of at least 60 ° C at a pressure above 1 bar without using an autoclave. Manufacturing method.   Blending a liquid curable resin and a curing agent having a melting point greater than 100 ° C. to form a liquid blend of the curable resin and the curing agent, configured for the blended curable resin and the curing agent Impregnating at least a portion of the fiber array to form a curable composite material, and thereafter curing the composite material to an elevated temperature at a pressure of 3 absolute bar or less to form a cured composite material. A method for producing a cured composite material.   The process according to any one of claims 1 to 9, wherein the blending is carried out at a temperature from 60 to 180 ° C, preferably from 80 to 160 ° C, more preferably from 90 to 150 ° C. .   Prior to fiber impregnation, the temperature of the blended curing agent and curable resin is higher than 100 ° C, preferably higher than 120 ° C, for less than 10 minutes, preferably less than 2 minutes, more preferably less than 1 minute, more 11. A process according to any one of claims 1 to 10, preferably higher than 140 <0> C.   12. A method according to any one of the preceding claims, wherein a vacuum is applied while the resin is blended.   13. A method according to any one of claims 6 to 12, wherein the constituent fibers are tabular, so that the constituent fibers form a once impregnated prepreg.   14. A method according to any one of claims 6 to 13, wherein the curable composite material is formed into an aerospace structural member.   15. A method according to any one of claims 6 to 14, wherein the curing process is carried out at a pressure of less than 2.0 absolute bar, preferably less than atmospheric pressure or greater than atmospheric pressure.   A curable composite material comprising a reinforced resin and a fiber array, wherein the reinforced resin is a liquid curable resin and a liquid at a temperature from 70 ° C to 150 ° C, preferably from 90 ° C to 140 ° C. A curable composite material comprising a blend with a solid curing agent dissolved in a curable resin.   At a temperature from 70 ° C. to 150 ° C., preferably from 90 ° C. to 140 ° C., the liquid curable resin and the curing agent are blended in-line or continuously, and the volume porosity is less than 2.0%, In a fiber array of reinforced resin, preferably prepared by forming a curable composite material having a porosity of less than 1.0% and then curing in a deautoclave at a temperature ranging from 60 ° C to 200 ° C. Use in.

Images